The present invention relates to weatherstrips, and more particularly to a migration inhibiting barrier for a weatherstrip and in a specific configuration, a layer for substantially precluding the migration of decomposition products, including odors and staining materials often resulting from blowing and curing agents used in formation of the weatherstrip.
In many weatherseal constructions it is often advantageous to incorporate a foam or sponge portion. The foam or sponge provides a number of advantages including accommodating relatively wide variances and tolerances. For sponge seals or seals having sponge components, desirable characteristics often include resistance to compression set, relatively low compression load deflection and light weight.
The weatherstrips having sponge components preferably have a good resistance to compression set. Compression set resistance refers to the ability of a material to resume its initial shape after being subjected to a compressive load. Failure to provide good compression set resistance may lead to poor sealing performance. The weatherseal should also be relatively soft and yielding. A low compression load deflection insures that a door or window can be closed without the need for excessive force and yet sufficiently compress the weatherstrip to form the necessary sealing interface. In addition, it is often desirable that the weatherstrip be as lightweight as possible, that is having a low density. Low-density thermoplastic and thermosetting foams have exhibited high compressibility, yet have sufficient compression set resistance to provide a good seal. To produce such low density foams, a substantial percentage of blowing agent is typically introduced into the elastomer to be foamed.
However, the formation process of such foamed material tends to retain a relatively large amount of decomposition products from the blowing agent in the formed product. The decomposition products from the blowing agent slowly leach (pass) from the foamed component of the seal. These decomposition products typically have an objectionable odor. The emanating odor is objectionable to both the installers of the weatherstrips and purchasers of products incorporating the strips. In addition, decomposition products from curing agents can stain or form staining materials. Migration of the staining materials through the seal can undesirably color the seal. As the time between manufacture of the weatherstrip and possession by the end consumer continually decreases, the downsteam assemblers and consumers experience increased amounts of decomposition product leaching.
Therefore, the need exists for a weatherstrip, having a foam or sponge portion, wherein decomposition products such as odors and staining materials from the formation process are substantially retained within the product. A need also exists for a foam weatherstrip that can be readily colored. A need exists for a migration inhibiting layer that can be disposed at a variety of locations in a weatherstrip. The need exists for a migration inhibiting layer that can substantially preclude the migration of decomposition products associated with formation of the weatherstrip.
The present invention provides a migration inhibiting layer that can be readily located as an interior layer or an exposed layer in a weatherstrip. The migration inhibiting layer can be disposed upon and bonded to an expanded elastomer such as a foam or sponge portion of a weatherstrip. In addition, the present migration inhibiting layer can be colored to provide an exposed or visible surface of a weatherstrip with an aesthetically pleasing color.
The migration inhibiting layer is constructed to reduce passage of decomposition products generated during formation of the weatherstrip. The decomposition products can be created from blowing or curing agents used in formation of the weatherstrip. The decomposition products can include objectionable odors, usually resulting from blowing agents, or staining materials, usually resulting from curing agents.
In a preferred configuration, the migration inhibiting layer is formed of a blend of a halogenated butyl and EPDM. One configuration of the migration inhibiting layer contemplates the use of chlorobutyl as the halogenated butyl. In a further configuration, the halogenated butyl-EPDM blend is sufficient to substantially preclude the diffusion of decomposition products from the cellular structure of the expanded elastomer. In a further configuration, the migration inhibiting layer, such as the halogenated butyl-EPDM blend can be colored to provide an aesthetically pleasing appearance to the weatherstrip such as on at least one of a dense or expanded elastomer portion of the weatherstrip.